Salt has spent decades being treated like the ultimate kitchen villain, and for good reason given how much of it hides in everyday processed meals and takeaways.
Pounding through too much of it steadily nudges your blood pressure up and puts unnecessary strain on your heart, so most of us are constantly told to ditch the shaker and cut back wherever we can. The catch is that your body actually depends on a regular supply of sodium to keep your muscles firing and your brain ticking over properly.
When levels plunge too low, whether through illness, certain medications, or sweating buckets during a hard workout, the fallout hits quickly with persistent headaches, heavy fatigue, and vicious muscle cramps. Spotting those warning signs makes it much easier to tell when your body is truly running on empty, rather than treating every single grain on your plate like poison.
Your body needs salt to function properly.
Salt is made up mainly of sodium, a mineral the body needs to stay healthy. Sodium helps your muscles move, your nerves send signals and your body keep the right balance of fluids. Without enough of it, these important jobs can’t be done properly.
Sodium is one of a group of minerals called electrolytes, which also includes potassium and magnesium. They work together to keep your body hydrated and functioning well. Your body usually manages these levels carefully, but sometimes they can fall out of balance.
Most people eat too much of it, however.
The NHS advises adults to have no more than 6g of salt a day, which is about a teaspoon. Most adults in the UK eat more than this. Around three quarters of the salt we eat is already in foods we buy, such as bread, breakfast cereals, ready meals and processed meats.
For most people, the main health concern is having too much salt rather than too little. Cutting down can help lower blood pressure and protect the heart. That’s why it’s important not to start adding extra salt unless you have a good reason or have been advised to.
Signs you may be low on salt
When sodium levels drop too low, it’s known as hyponatraemia. Early signs can include headaches, tiredness, weakness, muscle cramps and feeling sick. Some people also find they crave salty foods.
Other signs of being low on fluids and salt can include a dry mouth, feeling dizzy when you stand up, passing less urine and stomach cramps. In more serious cases, low sodium can cause confusion, vomiting, or seizures. If you or someone else has severe symptoms like these, get medical help straight away by calling 999 or going to A&E.
People who sweat a lot need more.
When you sweat, you lose both water and salt. People who exercise hard, especially for long periods, can lose a lot through sweat. The same goes for people who work outdoors or in hot places, and anyone spending time in very hot weather.
Drinking only plain water in very large amounts during long events such as marathons can make the problem worse, as it can dilute sodium levels in the blood. Endurance athletes may benefit from drinks that replace lost electrolytes. If you take part in long or intense exercise, ask a doctor or sports professional for advice on staying properly hydrated.
When you have a stomach bug, you also require extra salt.
Diarrhoea and vomiting can cause your body to lose lots of fluid and salt quickly. This can lead to dehydration, which can be especially serious for babies, young children and older people. It’s important to keep sipping fluids, even if you don’t feel like it.
Oral rehydration solutions, available from pharmacies, are designed to replace lost fluids, salt, and sugar in the right amounts. Ask your pharmacist which one is suitable for you or your child. Get medical advice if symptoms are severe, don’t improve, or you notice signs of dehydration such as very little urine.
Certain health conditions can impact salt levels.
Some health conditions mean people need more salt than usual. People with cystic fibrosis tend to lose more salt through their sweat and are often prescribed salt supplements. Those who’ve had part of their bowel removed, such as people with an ileostomy, may also lose more salt and fluid.
Certain medicines, including some water tablets and antidepressants, can lower sodium levels too. If you have one of these conditions or take regular medicines, follow the advice of your medical team. Never stop or change a medicine without speaking to your doctor first.
Low-carb diets make maintaining sodium levels extra important.
Very low-carbohydrate diets, such as the keto diet, can cause the body to lose more water and salt, especially in the early stages. Some people get tiredness, headaches and weakness, sometimes called keto flu. These symptoms can be linked to low electrolyte levels.
If you’re thinking of starting a very low-carb diet, speak to your GP first, particularly if you have a health condition or take medicine. A doctor or dietitian can help you plan a diet that keeps you healthy. Sudden, extreme changes to your diet are rarely a good idea.
Getting the balance right can be simple.
If you’ve been told you need more salt, there’s no need to pour it over every meal. Foods such as eggs, milk, cheese, seafood, celery, and beetroot naturally contain some sodium. Your doctor or dietitian can advise on the right amount for you.
Sports drinks are often high in sugar, so they’re not a good everyday choice. If you have high blood pressure, heart problems or kidney disease, don’t increase your salt without medical advice. If you’re worried your salt levels may be too low or too high, speak to your GP, who can check with a simple blood test.
